Liquid–liquid equilibria for the ternary system water + octane + 2-butyloxy-ethanol

• A ternary system water + octane + 2-butyloxyethanol was chosen.
• The fish-shaped phase diagram of the ternary system was reported.
• The upper and lower critical solution temperatures of the system were, respectively, 296.90 and 286.10 K.
• LLE data for this ternary system were determined at T = 283.15, 293.15 and 303.15 K under atmospheric pressure.
• The NRTL model was applied to correlate the experimental data.

Experiment of the fish-shaped phase diagram of the ternary water + octane + 2-butyloxy-ethanol system under atmospheric pressure was performed at constant water/octane mass ratio (1/1) to determine the upper critical solution temperature (UCST = 296.90 ± 0.05 K) and the lower critical solution temperature (LCST = 286.10 ± 0.05 K). The liquid–liquid equilibria of the water + octane + 2-butyloxy-ethanol system at 283.15, 293.15 and 303.15 K were measured under atmospheric pressure. At 283.15 and 303.15 K, there is only one two-liquid-phase-coexisting envelop in the triangle phase diagram. At 293.15 K, in-between the UCST and LCST, the system exhibits three two-liquid-phase-coexisting envelops and one three-liquid-phase-coexisting tie triangle in the triangle phase diagram. The experimental results of liquid–liquid equilibria were further correlated with the nonrandom two-liquid (NRTL) model.